Vane pump or motor



' Spt. 12, 1967 HfvPATEL 3,340,816

, VANE PUMP OR MOTQR FilGd. 0012. 1 1, l965 2 Sheets-Sheet l INVENTOR. HAP/4444 M PATEL Arraea/svs United States Patent Ohio Filed Oct. 11, 1965, Ser. No. 494,602 11 Claims. (Cl. 103136) This invention relates generally to pumps and motors and more particularly to a novel and improved vane pump or motor constructed to minimize manufacturing costs and to provide efficient operation with a minimum of maintenance.

The illustrated embodiment of this invention is a low cost air pump particularly suited for pumping air into the exhaust of an internal combustion engine to insure complete combustion of the engine exhaust gases and thereby eliminate a source of air pollution. The pump structure is arranged to minimize manufacturing costs and to provide a long substantially trouble free service life. It should be understood that although this invention is disclosed and described as applied to an air pump the invention is equally applicable to air motors and that the term pump when used in the claims is intended to embrace pumps, compressors and motors.

Vane pumps generally include a stator with a rotor journaled therein for rotation about an axis. The stator usually defines a rotor chamber or pumping chamber having a curved peripheral Wall of uniform cross-section shaped so that the vanes carried by the rotor sweep along the peripheral wall and cooperate with the rotor and stator to define separated chambers in which gas is either compressed or expanded depending upon whether the mechanism is a pump or a motor.

Close fits must be provided between the vanes and the stator to minimize leakage therepast. Also, a sealing zone must be provided between the stator and the rotor to eliminate leakage at this area. In the United States patent to Buckbee, No. 2,400,286, dated May 14, 1946, a vanetype machine is illustrated wherein the stator is formed with cylindrical recesses at the ends of the main chamber and cylindrical members afiixed to the ends of the rotor to provide an axially extending cylindrical sealing zone between the stator and rotor. In the machine of the type disclosed in this patent, however, the axially extending recesses are open at a radius equal to the minimum radius of a perihperal wall of the stator. It is necessary in such machines to form rotor slots which are closed at their ends in alignment with the chamber end walls to axially confine the vanes. Such a structure requires a rotor assembly constructed of at least three parts with the result that manufacturing costs are increased. Also differential expansion of the rotor or stator can result in a condition wherein the end walls of the slots do not remain in alignment with the stator end walls.

In a device incorporating the present invention cylindrical recesses are formed in the stator which have a radius less than the minimum spacing betweem the peripheral wall and the axis of rotation of the rotor. The rotor is formed of a single piece having vane receiving axial slots extending the entire length of the rotor and cylindrical end portions which closely fit the cylindrical recesses and provide the required seal between the rotor and stator. The vanes and slots are also proportioned so that the vanes extend inward past the recess in all rotor positions so that leakage does not occur under the ends of the vanes. Since the peripheral wall is spaced from the recesses in all zones the axial location of the vanes is provided by the end walls of the stator in all positions of rotor rotation.

The present invention therefore permits limited axial movement of the rotor relative to both the vanes and stator without introducing operating difficulties. Therefore, anti-friction ball bearings, which permit more axial freedom than radial freedom, may be used to axially locate the rotor. Generally such bearings have about five times as much axial freedom as radial freedom. Consequently, the manufacturing tolerances of the rotor are relatively easily maintained and the cost of rotor production is relatively low.

It is an important object of this invention to provide a novel and improved vane pump constructed and arranged to permit the use of low cost bearings and wherein the axial position of the vane is maintained by the stator in all rotor positions.

It is another important object of this invention to provide a novel and improved vane-type machine provided with an axially extending annular rotor seal, a bearing at one end of the rotor providing close radial control and limited axial freedom, a bearing at the other end of the rotor providing close radial control and unlimited axial freedom, in combination with a stator arranged to axially locate the vanes in all positions of rotor rotation.

It is still another object of this invention to provide a vane-type pump as set forth in the preceding object wherein two compression chambers are symmetrically lo cated with respect to the rotor axis thereby minimizing radial loads on the rotor bearings.

It is still another object of this invention to provide a novel and improved vane-type pump constructed and ar ranged to minimize the close tolerance manufacture of the elements and thereby reduce manufacturing costs.

Further objects and advantages will appear from the following description and drawings wherein:

FIGURE 1 is an end view of one embodiment of this invention with the drive pulley removed;

FIGURE 2 is an opposite end view of the pump illustrated in FIGURE 1;

FIGURE 3 is a longitudinal section taken along 3--3 of FIGURE 1; and, 1

FIGURE 4- is a cross-section taken along 4--4 of FIGURE 3.

The illustrated embodiment of this invention includes a stator 10 constructed of three major elementsa housing 11, a first end plate 12 and a second end plate 13. The housing 10 is formed with a pair of spaced mounting lugs 14- on one side and a single mounting lug 16 on the other side. The housing is also formed with a peripheral wall 17 defining the uniform cross-section rotor chamber I18. The peripheral wall 17 is symmetrical with respect to a rotor axis 19 having opposed zones 21 and 22 with a minimum spacing from the axis 19. This structure is best illustrated in FIGURE 4. From the zone 21 to the zone 24 the peripheral wall has an increasing spacing from the axis 19 followed by a decreasing spacing from the zone 24 to the zone 22. Similarly, from the zone 22 to the zone 23 there is an increase in spacing followed by a decrease in spacing from the zone 23 to the zone 21. Consequently, two compressing chambers 26 and 27 are provided on opposite sides of the stator. An outlet port 28 is provided in the stator housing 11 for the chamber 26 and an outlet port 29 is provided for the chamber 27. The ports open to tubular projections 31 each adapted to connect with a delivery hose. Cooling fins 32 extend along the exterior surface of the stator housing 11.

The first end plate 12 is formed with a flat end face 33 extending inwardly from the end face 34 of the stator housing to an axially extending cylindrical bore coaxial with the axis 19. The wall of the end plate 12 extends inwardly from the cylindrical bore 36 to a bore 37 which receives the outer race 38 of a ball bearing 39. The outer race 38 is seated against an inwardly extending shoulder 41 by a lip 42 spun over against the opposite end of the race 38 when the bearing is assembled in the end plate 12.

The end plate 13 is formed with a flat end face 43 extending inwardly from the end face 44 of the stator housing 11 to a cylindrical bore 46 which in the illustrated embodiment has the same diameter as the bore 36 and is also coaxial with the axis 19. From the bore 46 the end plate 13 extends inwardly to a bore 47 into which a sleeve bearing 48 is press fitted.

The two end plates 12 and 13 are provided with locating pins 48 which fit into bores in the end faces of the stator housing to provide exact location of the end plates relative to the housing and tie bolts 49 secured the end plates and housing together. The end plate 13 is provided with similar and opposed inlet ports 51 and 52 (best illustrated in FIGURE 4) with the inlet ports 51 open to the chamber 26 and the inlet ports 52 open to the chamber 27. A cover plate 53 is secured to the end plate 13 by a bolt 54 and cooperates therewith to define an inlet chamber 56 open to both of the ports 51 and 52. As best illustrated in FIGURE 2 the cover plate 53 is formed with a plurality of ports or openings 57 through which air can pass into the chamber 56. One group of openings 57 is located near the inlet port 51 and the other group near the port 52. A screen disc 58 retains filter material 59 within the cover plate '53 adjacent to the openings 57 to filter dirt or other foreign matter from the air entering the pump. A filter material 59 and the chamber 56 also functions as a muffler to reduce noise when the pump is operating.

A rotor shaft 61 extends through the inner race 62 of the bearing 39 with a close fit and is formed with a cylindrical bearing surface 63 of reduced diameter which fits into the sleeve bearing 48. A rotor 64 is formed with a through bore 66 closely fitting the shaft 61 and provided with a counter bore 67 which receives a lock ring 68 positioned in a lock ring groove 69. The opposite end of the rotor 64 is provided with an end face 71 engaging the inner race 62 of the bearing 39. A drive pulley 72 fits over the projecting end of the rotor shaft 61 and is clamped against the opposite side of the inner race 62 by a nut 73. With this structure the single nut 73 cooperates with the lock ring 68 to lock the rotor 64, relative to the rotor shaft 61, against the inner race 62 of the bearing 39 and at the same time lock the pulley 72 on the rotor shaft 61. Suitable keys 74 are utilized to lock the rotor shaft 61 against rotation relative to both the pulley 72 and rotor 64. The structure of the rotor shaft 61 is such that it can be machined from shaft stock with a minimum amount of machining since no collars or flanges are required. It is relatively simple to turn the bearing surface 63, the lock ring groove 69 and threaded end 76 on the shaft stock since the initial diameter of the stock is the maximum diameter of the shaft.

The rotor 64 is provided with a central portion 77 with a radius proportional so that its outer surface is close to the zones 21 and 22. The diameter of the central portion 77 is also greater than the diameter of the cylindrical bores 36 and 46 having an axial length less than the length of the stator housing 11 so that clearance is provided at 78 between the ends of the central portion 77 and the end walls 33 and 43. A cylindrical projection 79 is formed on the end of the rotor 64 adjacent the end plate 12 and extends into a cylindrical bore 36 with a minimum amount of clearance so that an annular seal is provided between the rotor and end plate at this location. A similar cylindrical surface 81 projects into the cylindrical bore 46 at the opposite end of the rotor and here again a minimum clearance is provided to provide a seal between the rotor and the end plate 13.

A simple ball bearing of the type 39 provides a high degree of accuracy as to radial location but much less accuracy as to axial location. In normal ball bearings the axial freedom play is about five times as great as the radial freedom. Consequently, the clearance between the cylindrical bore 36 and the cylindrical surface 79 can be relatively closely maintained without wear even though the bearing 39 permits the rotor 64 to move a limited amount in an axial direction. Similarly, the sleeve bearing 48 permits axial freedom but provides a high degree of accuracy as to the radial positioning of the opposite end of the rotor. Therefore, clearance between the cylindrical surface 81 and the cylindrical bore 46 can be closely maintained while axial freedom is not a close tolerance problem.

The rotor 64 is provided with a plurality of axially extending symmetrically arranged slots 82 each of which receives a vane 83. In the illustrated embodiment there are six slots 82 and vanes 83 symmetrically arranged around the axis 19. The vanes 83 have a length substantially equal to the length of the stator housing 11 and are proportioned to extend between the end faces 33 and 43 with a close fit. The exterior of the vanes 83 rides along the peripheral wall 17 with the centrifugal force of rotation maintaining engagement. Preferably, the vanes 83 are formed of a material which does not require lubrication and which provides minimum friction and minimum Wear. One suitable material is formed of cotton impregnated with a phenolic resin and carbon. However, other materials such as Teflon may be utilized in some instances.

The slots 82 extend inwardly to a radius less than the radius of the cylindrical surfaces 79 and 81 and extend the entire length of the rotor 64. Therefore, the ends of the vanes 83 cooperate with the cylindrical surfaces 79 and 81 at 86 and 87, respectively, to prevent leakage out along the slots. The vanes 83 have a radial extent at their ends greater than the spacing of the zones 23 and 24 from the axis 19 minus the radius of the cylindrical surfaces 79 and 81 to insure this sealing function. Also, the minimum spaced zones 21 and 22 of the peripheral wall 17 are spaced from the axis 19 by a distance greater than the radius of the cylindrical surfaces 79 and 81 so that the ends 87 and 88 of the vanes 83 remain in engagement with the associated end faces 33 and 43 and are axially positioned thereby in all rotor positions.

The bearings loads on the bearings 39 and 48 are minimized because of the two opposed compression chambers 26 and 27. Therefore, bearing life is satisfactory even though low cost bearings are utilized. Preferably the end plates 12 and 13, the stator housing 11 and the rotor 64 are die cast from aluminum for light weight. Since the areas of close tolerances are limited the machining costs of finishing these elements is low and the manufacturing costs are, therefore, minimized.

Although a preferred embodiment of this invention is illustrated, it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention as defined in the following claims.

I claim:

1. A vane pump comprising a stator having a pcripheral wall and opposed end walls defining a rotor chamber, a rotor journaled in said stator for rotation about an axis, a cylindrical recess in each end wall coaxial with said axis each having a radius less than the minimum spacing between said peripheral wall and said axis, said rotor being formed with end projections'closely fitting said recesses with clearance sufficiently small to prevent substantial fluid flow therebetween, a plurality of axial slots having inner walls spaced from said axis a distance less than the radius of said recesses, said slots projecting beyond said end walls, a vane in each slot closely fitting said end walls and said peripheral wall and extending inwardly past the walls of said recesses in all rotor positions, and an inlet and outlet open to said chamber.

2. A vane pump as set forth in claim 1 wherein said rotor is provided with a central portion between said end walls having a radius approaching the minimum spacing between said peripheral wall and axis.

3. A vane pump as set forth in claim 1 wherein spaced bearings are mounted in said stator and operate to support said rotor for its rotation about said axis, said bearing permitting a limited extent of axial movement of said rotor relative to said stator.

4. A vane pump as set forth in claim 3 wherein one.

of said bearings prevents axial movement beyond said limit extent and the other of said bearings does not provide axial restraint.

5. A vane pump as set forth in claim 4 wherein said one bearing is an antifriction ball bearing and said other bearing is a sleeve bearing.

6. A device of the character described comprising a stator having a peripheral wall and opposed parallel end walls perpendicularly intersecting said peripheral wall and cooperating therewith to define a rotor chamber, a rotor journaled in said stator for rotation about an axis perpendicular to said end walls, said stator and rotor being formed with mating cylindrical surfaces adjacent said end walls having a radius less than the minimum spacing between said peripheral wall and said axis and provided with sufliciently small clearance to prevent substantial leakage therebetween, a plurality of axial slots having inner walls spaced from said axis a distance less than the radius of said cylindrical surfaces at least adjacent said end walls, said slots projecting beyond said end walls, a vane in each slot closely fitting said end walls and said peripheral wall and extending inwardly past said cylindrical surfaces at least adjacent to said end walls in all rotor positions, and an inlet and outlet open to said chamber.

7. A device as set forth in claim 6 wherein peripheral wall defines a plurality of similar chambers symmetrically positioned around said axis, and said vanes each sweep each chamber during each rotor revolution.

8. A device of the character described comprising a stator having a peripheral wall and parallel opposite end walls defining a rotor chamber, a rotor journaled in said stator for rotation about an axis, a cylindrical recess in each end wall coaxial with said axis, the radius of each recess being less than the minimum spacing between said peripheral wall and said axis, a first bearing supporting one end of said rotor for rotation about said axis and retaining said one end of said rotor against substantial axial movement, a second bearing supporting the other end of said rotor for rotation about said axis without axial restraint, said rotor including a central portion with a radius greater than the radius of said cylindrical recesses and cylindrical ends one closely fitting each recess, a plurality of axial slots in said central portion extending into said cylindrical ends, a vane in each slot engaging said peripheral wall and said end walls in all rotor positions, and an inlet and an outlet in said stator communicating with said rotor chamber.

9. In a device of the character described, a stator, a rotor journaled for rotation in said stator, said stator and rotor cooperating to define a plurality of similar symmetrically arranged chambers, a plurality of vanes carried by said rotor each operating to sweep each chamber during each rotor revolution, said stator including an annular housing and an end plate, a plurality of passages in said end plate with one open to the end of each chamber, a plurality of passages in said stator with one open to the peripheral wall of each chamber, one opening in each chamber admitting fluid thereto and the other opening in each chamber exhausting fluid therefrom.

10. A device as set forth in claim 9 wherein the passages in said end plate admit fluid to the associated chambers, and filter and muffler means are mounted on said end plate through which the fluid flows before entering said chamber.

11. A rotor structure for a vane pump comprising a pair of spaced bearings, a shaft journaled in said bearings, said shaft having a central portion between said bearings of uniform diameter equal to the maximum diameter of said shaft, a rotor body formed with a through bore closely fitting said central portion, a lock ring groove in said shaft adjacent one end of said rotor, a lock ring in said groove engaging a shoulder on said rotor limiting axial movement of said rotor relative to said shaft in a direction toward said one end, the other end of said rotor engaging the adjacent bearing, a pulley on said shaft engaging the side of said adjacent bearing opposite said rotor, and threaded means on said shaft pressing said pulley relative to said shaft toward said adjacent bearing whereby said lock ring and threaded means cooperate to prevent axial movement between said shaft, pulley, rotor and adjacent bearing.

References Cited UNITED STATES PATENTS 1,409,548 3/1922 Imholf et al 103-136 2,400,286 5/1946 Buckbee 230152 2,544,987 3/1951 Gardiner et al 103135 2,623,471 12/1952 Hartmann 103136 2,678,156 5/1954 Henderson 230-152 2,825,287 3/1958 Ostwald 103-136 2,962,977 12/ 1960 Klessig et al. n 103220 3,070,032 12/ 1962 Rohde 103-220 3,270,955 9/1966 Huyser et al 230152 DONLEY J. STOCKING, Primary Examiner.

WILBUR I. GOODLIN, Examiner. 

1. A VANE PUMP COMPRISING A STATOR HAVING A PERIPHERAL WALL AND OPPOSED END WALLS DEFINING A ROTOR CHAMBER, A ROTOR JOURNALED IN SAID STATOR FOR ROTATION ABOUT AN AXIS, A CYLINDRICAL RECESS IN EACH END WALL COAXIAL WITH SAID AXIS EACH HAVING A RADIUS LESS THAN THE MINIMUM SPACING BETWEEN SAID PERIPHERAL WALL AND SAID AXIS, SAID ROTOR BEING FORMED WITH END PROJECTIONS CLOSELY FITTING SAID RECESSES WITH CLEARANCE SUFFICIENTLY SMALL TO PREVENT SUBSTANTIAL FLUID FLOW THEREBETWEEN, A PLURALITY OF AXIAL SLOTS HAVING INNER WALLS SPACED FROM SAID AXIS A DISTANCE LESS THAN THE RADIUS OF SAID RECESSES, SAID SLOTS PROJECTING BEYOND SAID END WALLS, A VANE IN EACH SLOT CLOSELY FITTING SAID END WALLS AND SAID PERIPHERAL WALL AND EXTENDING INWARDLY PAST THE WALLS OF SAID RECESSES IN ALL ROTOR POSITIONS, AND AN INLET AND OUTLET OPEN TO SAID CHAMBER. 